Inkjet thermal actuator with parallel current paths

Abstract

An inkjet printhead is disclosed. The printhead has an array of ink chambers. Each ink chamber has a nozzle and a thermal actuator for generating vapor bubbles to eject ink through the nozzle. The thermal actuator has a pair of contacts and at least two parallel current paths between the contacts. Each of the current paths has a plurality of heater elements for nucleating a vapor bubble.

1. An inkjet printhead comprising an array of ink chambers, each ink chamber comprising:
 a plurality of nozzles; and 
 a thermal actuator for generating vapour bubbles to eject ink through the nozzles, the thermal actuator comprising a pair of contacts and at least two parallel current paths between the contacts, each of the current paths having a plurality of heater elements connected in series, wherein the heater elements are suspended within the chamber. 
 
     
     
       2. An inkjet printhead according to  claim 1 , wherein respective heater elements are associated with respective nozzles. 
     
     
       3. An inkjet printhead according to  claim 1  wherein the heater elements nucleate bubbles simultaneously. 
     
     
       4. An inkjet printhead according to  claim 1  wherein the thermal actuator has a cross bracing structure extending between intermediate points on the parallel current paths. 
     
     
       5. An inkjet printhead according to  claim 4  wherein the cross bracing structure provides increased thermal inertia to the current paths where the cross bracing structure connects to the current paths. 
     
     
       6. An inkjet printhead according to  claim 4  wherein the cross bracing structure provides a droplet stem anchor. 
     
     
       7. An inkjet printhead according to  claim 1  wherein the thermal actuator is formed from TiAlN. 
     
     
       8. An inkjet printhead according to  claim 1  wherein each of the ink chambers has two nozzles. 
     
     
       9. An inkjet printhead according to  claim 1  wherein the nozzles in each chamber are arranged in a line parallel to the length of the heater element, with the central axes of the nozzles being regularly spaced along the heater element. 
     
     
       10. An inkjet printhead according to  claim 1  wherein the nozzles are elliptical. 
     
     
       11. An inkjet printhead according to  claim 10  wherein the major axes of the elliptical nozzles are aligned.